1. Field of the Invention
The invention relates to a 7-methyl-3-methylene-7-octenal acetal compound and methods for producing an aldehyde compound and an ester compound using the acetal compound.
2. Related Art
3,7-Dimethyl-2,7-octadienal and a corresponding alcohol, 3,7-dimethyl-2,7-octadienol are widely applied as floral perfumes and fruit flavors. Their regioisomers having double bonds at different positions, 7-methyl-3-methylene-7-octenal and 7-methyl-3-methylene-7-octenol, are expected to be applied in the same fields. Stoyanova et al. have reported that 7-methyl-3-methylene-7-octenal exists in the essential oil of seeds of Amomum tsaoko (Godoshnik na Visshiya Khimikotekhnologicheski Institut, Sofiya, 31, 203 (1991), CODEN: GVKIAH, ISSN: 0489-6211).
Quadraspidiotus perniciosus (generic name: San Jose Scale, hereinafter abbreviated as “SJS”) is widely distributed in the world, damages fruit trees and ornamental trees, especially deciduous fruit trees, and thus is an economically critical insect pest. Gieselmann et al. and Anderson et al. have found that the sex pheromone of SJS contains three active components of 7-methyl-3-methylene-7-octcnyl propionate, (Z)-3,7-dimethyl-2,7-octadienyl propionate, and (E)-3,7-dimethyl-2,7-octadienyl propionate (Gieselmann et al., J. Chem. Ecol., 5, 891 (1979), Anderson et al., J. Chem. Ecol., 5, 919 (1979), and Anderson et al., J. Chem. Ecol., 7, 695 (1981)).
An insect sex pheromone is a biologically active substance that is commonly secreted by female individuals to attract male individuals, and a small amount of the sex pheromone shows strong attractive activities. A sex pheromone has been widely used as means for forecasting insect emergence or for ascertaining regional spread (invasion into a specific area) and as means for controlling an insect pest. As the means for controlling the insect pest, control methods called mass trapping, lure and kill (another name: attract and kill), lure and infect (another name: attract and infect), and mating disruption are widely used in practice. To utilize a sex pheromone, it is necessary to economically produce a required amount of the sex pheromone product for basic research and also for application.
Synthetic examples of the SJS sex pheromones include the following Syntheses (a) to (f):
Synthesis (a): syntheses of 7-methyl-3-methylene-7-octenyl propionate and (Z)-3,7-dimethyl-2,7-octadienyl propionate by Anderson et al., containing addition of an organocuprate reagent to an alkyne as the key reaction (Anderson et al., J. Chem. Ecol., 5, 919 (1979));
Synthesis (b): syntheses of 7-methyl-3-methylene-7-octenyl propionate, (Z)-3,7-dimethyl-2,7-octadienyl propionate and (E)-3,7-dimethyl-2,7-octadienyl propionate by Weiler et al., containing a one-carbon homologation step from a β-keto ester compound: 7-methyl-3-oxo-7-octenoate (Weiler et al., Can. J. of Chemistry, 71, 1955 (1993));
Synthesis (c): synthesis of 7-methyl-3-methylene-7-octenyl propionate by Weedon et al., containing photochemical regioisomerization of a double bond from an α,β-unsaturated ester to a β,γ-unsaturated ester as the key reaction (A. C. Weedon et al., Tetrahedron Letters, 27, 5555 (1986));
Synthesis (d): synthesis of 7-methyl-3-methylene-7-octenyl propionate by Zhang et al. containing formation of exo-methylene as the key reaction through reduction of an allylic chloride obtained by chlorination involving isomerization of a trisubstituted double bond (H. S. Zhang et al., Chinese Chemical Letters, 2, 611 (1991), and Zhang et al., Huaxue Tongbao, 40, (1994));
Synthesis (c): synthesis of 7-methyl-3-methylene-7-octenyl propionate through alkylation of a dianion of 3-methyl-3-buten-1-ol by Anderson et al. and Chong et al. (Anderson et al., J. Chem. Ecol., 7, 695 (1981), and J. M. Chong et al., J. of Org. Chem., 66, 8248 (2001)); and
Synthesis (f): non-selective synthesis of 7-methyl-3-methylene-7-octenyl propionate through an allylic chloride mixture by Veselovskii et al. (V. V. Veselovskii et al., Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 3, 591 (1990)).